Separator for fuel cell

Abstract

A separator for a fuel cell includes multiple gas passages arranged side by side on a facing surface, and multiple cooling passages provided on a cooling surface. Each cooling passage is located between adjacent ones of the gas passages. The gas passages include multiple upstream passages arranged side by side, a merging portion, and a downstream passage that extends from the merging portion. The cooling surface includes a downstream end portion and a groove. The downstream end portion is a section in one of the cooling passages. The section is located between adjacent ones of the upstream passages and at an end portion of the cooling passage on a downstream side in a flow direction of the coolant. The groove connects the downstream end portion to another one of the cooling passages that is adjacent to the downstream end portion with one of the gas passages in between.

What is claimed is: 
     
         1 . A separator for a fuel cell, comprising:
 multiple gas passages arranged side by side on a facing surface configured to face a power generating unit of the fuel cell, the gas passages being configured to allow reactant gas to flow through the gas passages; and   multiple cooling passages provided on a cooling surface that is on a side opposite to the facing surface, each cooling passage being located between adjacent ones of the gas passages and being configured to allow a coolant to flow through the cooling passage, wherein   an upstream side and a downstream side in a flow direction of the reactant gas in each gas passage are defined as an upstream side and a downstream side, respectively,   the gas passages include:
 multiple upstream passages arranged side by side; 
 a merging portion that is configured such that the reactant gas flowing through at least two of the upstream passages merges at the merging portion; and 
 a downstream passage that extends from the merging portion toward the downstream side, and 
   the cooling surface includes:
 a downstream end portion, the downstream end portion being a section in one of the cooling passages, the section being located between adjacent ones of the upstream passages and at an end portion of the cooling passage on a downstream side in a flow direction of the coolant; and 
 a groove that connects the downstream end portion to another one of the cooling passages that is adjacent to the downstream end portion with one of the gas passages in between. 
   
     
     
         2 . The separator for the fuel cell according to  claim 1 , wherein the groove is one of at least two grooves, the grooves being provided in portions of the cooling surface that are on a side opposite to two of the upstream passages adjacent to the downstream end portion. 
     
     
         3 . The separator for the fuel cell according to  claim 2 , wherein
 the downstream end portion includes an axis that extends linearly, and   the arrangement of two of the upstream passages that are adjacent to the downstream end portion is symmetrical with respect to the axis.   
     
     
         4 . The separator for the fuel cell according to  claim 1 , wherein
 the downstream end portion includes an axis that extends linearly,   two of the upstream passages that are adjacent to the downstream end portion respectively include diagonal portions, the diagonal portions being diagonal with respect to the axis such that the distance between the diagonal portions decreases toward the merging portion, and   the groove is provided in a portion of the cooling surface that is on a side opposite to each of the diagonal portions.   
     
     
         5 . The separator for the fuel cell according to  claim 1 , wherein
 the facing surface includes a protrusion in a portion of the facing surface that is on a side opposite to the portion in which the groove is provided, the protrusion protruding into the gas passage, and   the protrusion is inclined such that a protruding amount increases toward the downstream side.